Multi-point unloading closed belt conveyor unloading point dust suppression method and dust suppression unloading device

Abstract

The invention relates to a dust suppression method for a discharging point of a multi-point discharging closed belt conveyor and a dust suppression discharging device.The dust suppression method comprises the steps that a belt conveyor discharging collision dust raising experiment device is built in a laboratory, and a belt conveyor discharging collision dust raising experiment is carried out; the conveying speed, the collision angle and the grain unloading height of the belt conveyor with the minimum collision flying dust are determined; the unloading device is arranged in the unloading point of the closed belt conveyor according to the conveying speed, the collision angle and the grain unloading height, so that collision flying dust in the unloading process of the unloading point of the closed belt conveyor for multi-point unloading is reduced, dust overflow of the belt conveyor is effectively reduced, the dust removal and air suction amount of equipment is reduced, the energy consumption is reduced, and the production efficiency is improved. And potential safety hazards such as powder explosion are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of grain material conveying equipment, and particularly relates to a dust suppression method and a dust suppression unloading device for a multi-point unloading closed belt conveyor at the unloading point. Background Art

[0002] A closed belt conveyor is a transportation device that uses a conveyor belt moving in a closed housing to convey bulk materials to a predetermined target. It has the advantages of low cost, mature technology, strong sealing performance, less dust pollution, simple and easy operation, etc. Therefore, closed belt conveyors are widely used in the processes of grain transfer, loading, warehousing, and outloading.

[0003] With the continuous expansion of the scale of grain depots, a grain depot usually consists of multiple granaries. When feeding grain into the granaries, it is usually fed into the granaries from the top of the granaries. Currently, when feeding grain into the granaries, multiple closed belt conveyors are usually inclined and overlapped one by one to achieve multi-bin feeding. The overall height is very large when reaching the end, and the pedestrian corridor also needs to be made inclined, which is cumbersome, has poor safety, and is inconvenient. For this reason, technicians have developed a convenient multi-point unloading device, such as a Chinese invention patent with the patent number ZL2016107624541 and the patent name "Belt conveyor throwing and distributing unloading device", and a Chinese invention patent application with the application number 2020102188650 and the name "Four-way unloading device for belt conveyor". The unloading device can realize the intermediate unloading of the belt conveyor, so as to achieve that one conveyor can simultaneously feed grain into multiple granaries, that is, one belt conveyor is arranged on the tops of multiple granaries, and multiple unloading devices are arranged on the belt conveyor, with one unloading device corresponding to one granary, to achieve multi-point unloading of one belt conveyor. When a certain granary needs to be fed with grain for warehousing, only the unloading device corresponding to this granary needs to be opened, and the grain transported on the belt conveyor enters the granary from this unloading device.

[0004] However, the existing multi-point unloading closed belt conveyor used for grain warehousing has the following defects when in use: 1. When the grain material falls from the high-position roller into the unloading device, the grain material collides with the wall plate of the unloading device, generating a large amount of dust diffusion. Since the belt conveyor is located in a closed space, the dust generated by the collision of the grain material and the unloading device is likely to accumulate inside the conveyor, posing a safety hazard, accelerating the wear of the conveyor belt and other mechanical equipment, increasing the maintenance cost, affecting the service life of the closed belt conveyor. In addition, the dust in the closed environment also has an explosion risk.

[0005] 2. The existing unloading devices of multi-point unloading closed belt conveyors are large in volume, and the production manufacturing cost, transportation cost, and installation cost are all very high.

[0006] 3. When the existing enclosed belt conveyor with multi-point unloading is in use, at the lap joint of two adjacent conveyor belts or at the unloading point, during unloading or throwing, it is inevitable that grain materials will spill. Some of the spilled grain materials will fall on the lower conveyor belt and be conveyed to the head of the belt conveyor, forming accumulated materials. In addition, some of the spilled grain materials will accumulate on the bottom plate of the closed housing and are difficult to clean. Especially when the conveyor is installed on the top of the granary, the cleaning operation is even more difficult. And the long-term accumulation of grain materials is prone to mildew and deterioration, affecting the quality of grain materials. Summary of the Invention

[0007] To sum up, in order to overcome the deficiencies of the prior art, the present invention provides a dust suppression method for the unloading point of a multi-point unloading enclosed belt conveyor. By conducting a collision dust-raising experiment, it determines the collision installation angle of the unloader that can reduce collision dust-raising, the conveying speed of the belt conveyor, and the installation distance between the unloader and the high-position drum, thereby reducing the collision dust-raising during the unloading process at the unloading point of the multi-point unloading enclosed belt conveyor, effectively reducing the dust spillage of the belt conveyor, reducing the dust suction volume of the equipment for dust removal, saving energy consumption, and reducing potential safety hazards such as dust explosion. At the same time, the present invention also provides a dust suppression unloading device.

[0008] To solve the above technical problems, the technical solution of the dust suppression method provided by the present invention is realized as follows: A dust suppression method for the unloading point of a multi-point unloading enclosed belt conveyor, which includes the following steps: S1. Build a belt conveyor unloading collision dust-raising experiment device in the laboratory and conduct a belt conveyor unloading collision dust-raising experiment to determine the conveying speed, collision angle, and unloading height of the belt conveyor with the least collision dust-raising; S2. Install an unloader in the enclosed belt conveyor according to the conveying speed, unloading height, and collision angle of the belt conveyor obtained in step S1.

[0009] Preferably, the belt conveyor unloading collision dust-raising experiment in step S1 includes the following steps: S11. Prepare experimental grain samples S111. Prepare a certain amount of grain particles with plump grains, no shriveled grains, and no broken grains; S112. Add a certain amount of tracer particles to the grain particles in step S111 and mix them evenly to obtain experimental grain samples. After equally dividing the obtained grain samples, store them in a constant temperature and humidity box; S12. Build the experimental device S121. Arrange a belt conveyor with adjustable height and speed; S122. Set an angle-adjustable baffle corresponding to the unloading end of the belt conveyor in step S121; S123. Arrange the PIV test system; S13. Obtain the baffle installation angle with the least collision dust S131. Set the height difference between the discharge end of the belt conveyor and the baffle plane, set the motor frequency corresponding to the conveying speed, set the installation angle of the baffle, calibrate the PIV test system, and start the belt conveyor; S132. After the belt conveyor runs stably, add a certain amount of the grain sample obtained in step S11 to the belt conveyor; S133. When the grain sample is discharged and collides with the baffle from the discharge end of the belt conveyor, the PIV test system conducts experimental shooting to obtain multiple corresponding optical photos of the grain sample colliding with the baffle; S134. Adjust the baffle installation angle multiple times, and calibrate the PIV test system. Repeat steps S132 - S134 to obtain multiple groups of optical photos of the grain sample colliding with the baffle with the same height difference between the discharge end of the belt conveyor and the baffle plane, the same belt conveyor conveying speed, and different baffle installation angles; S135. Use the visualization post - processing software Tecplot to conduct comparative analysis on the optical photos obtained in step S134 to obtain the velocity trace map of the dust collision diffusion when the grain sample collides with the baffle; S136. Compare and analyze the optical photos obtained in step S134 and the velocity trace map obtained in step S135 to obtain the baffle installation angle with the least collision dust when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the belt conveyor conveying speed is the same; S14. Obtain the conveying speed with the least collision dust S141. Set the height difference between the discharge end of the belt conveyor and the baffle plane, set the motor frequency corresponding to the conveying speed, set the installation angle of the baffle, calibrate the PIV test system, and start the belt conveyor; S142. Repeat steps S132 - S133 to obtain multiple optical photos of the grain sample colliding with the baffle; S143. Adjust the motor frequency of the belt conveyor multiple times, and calibrate the PIV test system. Repeat steps S132 - S134 to obtain multiple groups of optical photos of the grain sample colliding with the baffle with the same height difference between the discharge end of the belt conveyor and the baffle plane, the same baffle installation angle, and different belt conveyor conveying speeds; S144. Repeat steps S135 - S136 to obtain the conveying speed of the belt conveyor with the least collision dust when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the baffle installation angle is the same; S15. Obtain the height difference between the discharge end of the belt conveyor and the baffle plane with the least collision dust S151. Set the height difference between the discharge end of the belt conveyor and the baffle plane, set the motor frequency corresponding to the conveying speed, set the installation angle of the baffle, calibrate the PIV test system, and start the belt conveyor; S152. Repeat steps S132 - S133 to obtain multiple optical photos of the grain sample colliding with the baffle; S153. Adjust the height difference between the discharge end of the belt conveyor and the baffle plane multiple times, calibrate the PIV test system, and repeat steps S132 - S134 to obtain multiple optical photos of the grain sample colliding with the baffle under the conditions of the same conveying speed, the same baffle installation angle, and different height differences between the discharge end of the belt conveyor and the baffle plane; S154. Repeat steps S135 - S136 to obtain the height difference between the discharge end of the belt conveyor and the baffle plane with the minimum collision dust emission when the baffle installation angles are the same.

[0010] Preferably, in step S112, the tracer particles are micron - sized solid dust.

[0011] Preferably, in step S121, the height adjustment range of the belt conveyor is 0.1 m - 2.0 m, and the speed adjustment range is 2.1 m / s - 4.1 m / s.

[0012] Preferably, in step S122, the angle adjustment range of the baffle with respect to the horizontal plane is 0 - 180°.

[0013] Preferably, the PIV test system includes a laser illumination device, a CCD camera, a synchronous controller, and a computer equipped with an image analysis system. The lens of the CCD camera faces the baffle directly, the laser illumination device faces the baffle directly, the synchronous controller is communicatively connected to the CCD camera and the laser illumination device, and the CCD camera is communicatively connected to the computer equipped with the image analysis system.

[0014] The technical solution of the dust - suppressing discharge device provided by the present invention is realized as follows: A dust suppression and discharging device, comprising: a housing, a high-position roller, a low-position roller, a high-position conveyor belt, a low-position conveyor belt and a discharger. A high-position roller and a low-position roller are arranged in the housing. The high-position roller is located at the upper part of the housing, and the low-position roller is located at the lower part of the housing. A height difference is formed between the high-position roller and the low-position roller. The high-position roller is located at the discharging end of the high-position conveyor belt, and the low-position roller is located at the starting end of the low-position conveyor belt. An inclined discharger is arranged between the high-temperature roller and the low-position roller. The discharger has a discharging housing, a feeding port at the upper end of the discharging housing, a discharging port at the lower end of the discharging housing and discharging ports on both sides of the discharging housing. The discharging port of the discharger corresponds to the low-position conveyor belt. The discharging ports of the discharger are communicated with the discharging boxes on both sides of the housing. The feeding port and the discharging port are communicated to form a discharging channel, and the feeding port and the discharging ports are communicated to form a discharging passage. A discharging hopper capable of flipping relative to the discharging housing and a driving device for driving the discharging hopper to flip are arranged in the discharging housing. The flipping of the discharging hopper realizes the switching between the discharging channel and the discharging passage. A receiving hopper arranged in an inclined manner is provided in the feeding port of the discharger. The included angle between the receiving plate of the receiving hopper and the horizontal line is a, and the height difference between the receiving plate and the upper end of the high-position roller is h. The included angle a and the height h are both determined by the above dust suppression method.

[0015] Preferably, the included angle a is 45 - 60°.

[0016] Preferably, the height h is 200 - 300 mm.

[0017] Preferably, a collecting port with an opening downward is provided at the lower end of the housing. A cleaning housing is arranged below the collecting port. A cleaning feeding port communicated with the collecting port is provided on the top plate of the cleaning housing. A collecting plate is arranged in the cleaning housing. Both sides of the collecting plate are connected to the side plates of the cleaning housing. A cleaning discharging port is provided at the lower end of one side of the cleaning housing. A cleaning conveying device is arranged in the cleaning housing. The cleaning conveying device is used to convey the materials received by the collecting plate to the cleaning discharging port. The cleaning discharging port is communicated with the feeding port of the return housing. The return housing is a square annular hollow housing. The low-position conveyor belt passes through the inner ring square hole of the square annular housing. An upward-opening return discharging port is provided on one side of the return housing above the low-position conveyor belt. The return discharging port corresponds to the upper conveyor belt of the low-position conveyor belt. A return conveying device is arranged in the return housing. The return conveying device conveys the materials conveyed by the cleaning conveying device to the upper conveyor belt of the low-position conveyor belt.

[0018] Preferably, the cleaning conveying device is a cleaning scraper and a cleaning chain mechanism arranged in the cleaning housing. Both ends of the cleaning scraper are respectively connected to the chains of the two cleaning chain mechanisms. The lower end of the cleaning scraper contacts the top surface of the collecting plate. The two cleaning chain mechanisms drive the cleaning scraper to move, and the cleaning scraper pushes the materials on the collecting plate.

[0019] Preferably, the discharge hopper includes a bottom plate and arc-shaped baffles fixed on both sides of the bottom plate. A rotating shaft is provided outside the arc-shaped baffles, and the rotating shafts on the two arc-shaped baffles are arranged coaxially. The rotating shaft passes through the discharge housing and is connected to a driving device, and the driving device drives the rotating shaft to drive the arc-shaped baffles and the bottom plate to turn over.

[0020] Preferably, two receiving hoppers are arranged in parallel in the feed inlet of the discharge housing. The receiving hopper is a funnel-shaped structure surrounded by a receiving plate, an inner wall plate, an outer wall plate and a baffle plate. The receiving plate and the baffle plate are arranged opposite to each other, and the inner wall plate and the outer wall plate are arranged opposite to each other. The inner cavity of the receiving hopper forms a feed channel. On both sides of the discharge outlet of the discharge housing, there are discharge plates arranged obliquely downward from outside to inside, and the two discharge plates respectively correspond to the outer wall plates of the two receiving hoppers. The discharge opening of the discharge housing is provided with a discharge plate arranged obliquely downward from inside to outside, and the discharge plates of the two discharge openings respectively correspond to the inner wall plates of the two receiving hoppers. When the discharger discharges, the bottom plate of the discharge hopper fits with the inner wall plate and the discharge plate to form a discharge channel, and the feed inlet of the discharge housing is communicated with the discharge outlet. When the discharger discharges materials, the bottom plate of the discharge hopper fits with the outer wall plate and the discharge plate to form a discharge channel, and the feed inlet of the discharge housing is communicated with the discharge outlet.

[0021] The beneficial effects of the present invention are as follows: 1. Through the collision dust-raising experiment, the present invention determines the installation angle of the discharger capable of reducing collision dust-raising, the installation distance between the discharger and the high-position roller, etc., so as to reduce the dust-raising during the discharging process at the discharging point of the multi-point discharging enclosed belt conveyor, thereby effectively reducing the dust spillage of the belt conveyor, reducing the dust suction air volume of the equipment for dust removal, saving energy consumption, and reducing safety hazards such as powder explosion.

[0022] 2. The receiving hopper and the discharger of the dust suppression discharging device of the present invention are arranged obliquely. The included angle between the receiving plate of the receiving hopper and the horizontal line is a, and the included angle a is 45-60°. Within this range, when the discharging end of the belt conveyor discharges, the throwing trajectory of the grain material is close to the plane of the receiving plate. The throwing kinetic energy of the grain particles is more converted into sliding along the baffle direction, with less collision and less generation of collision dust. The dust is mainly dust-raising, and the movement trend of the dust is downward along the direction of the receiving plate, thereby reducing the diffusion of dust in the environment.

[0023] 3. The height difference between the lower edge of the receiving plate and the upper end of the high-position roller of the present invention is 200-300 mm. At this installation height, when the grain material is discharged, the kinetic energy of the grain particles is relatively low, and the collision dust generated when hitting the receiving plate is less, and the amount of dust-raising is also less, and the dust diffusion range is small. As the height difference increases, when the belt conveyor discharges materials, the falling height of the grain material increases, and the kinetic energy of the grain particles will increase, resulting in more collision dust and dust-raising. If the height difference is too small, it is not conducive to the installation and maintenance of the discharger.

[0024] 4. The receiving hopper and the discharger of the dust suppression and discharging device of the present invention are arranged obliquely, which can effectively reduce the volume of the discharging point of the multi-point discharging enclosed belt conveyor, thereby reducing the equipment installation space, saving the production and transportation costs, and improving the market competitiveness of the product.

[0025] 5. A receiving plate and a cleaning and conveying device are arranged below the aggregate inlet of the housing of the dust suppression and discharging device of the present invention. The grain materials scattered during the discharging process from the high-position conveyor belt to the low-position conveyor belt or from the high-position conveyor belt to the granary fall from the aggregate inlet onto the aggregate plate, and then enter the return housing under the action of the cleaning and conveying device, and then are re-conveyed onto the low-position conveyor belt under the action of the return conveying device and are re-conveyed by the low-position conveyor belt, thereby effectively solving the problem of accumulated materials in the housing of the dust suppression and discharging device, ensuring the normal and stable operation of the conveyor, reducing the wear of the conveyor belt, lowering the operation and maintenance costs, and ensuring the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic structural diagram of the experimental device of the present invention; Figure 2 is a schematic structural diagram of the dust suppression and discharging device of the present invention; Figure 3 is of the present invention Figure 2 schematic view in the direction A; Figure 4 is a schematic structural diagram of the return conveying device of the present invention; Figure 5 is a schematic structural diagram of the discharger of the present invention in the discharging state; Figure 6 is of the present invention Figure 5 schematic view in the section B-B; Figure 7 is a schematic view of the discharger of the present invention in the discharging state; Figure 8 are optical photos of the corn sample colliding with the baffle when the installation angles of the baffle are 30°, 45°, 60°, 120°, 135°, and 150° respectively; Figure 9 are velocity trace diagrams of the dust generated when the corn sample collides with the baffle when the installation angles of the baffle are 30°, 45°, 60°, 120°, 135°, and 150° respectively; Figure 10 are optical photos of the corn sample colliding with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, 4.1 m / s, and 4.9 m / s respectively; Figure 11 are velocity trace diagrams of the diffused dust generated when the corn sample collides with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, 4.1 m / s, and 4.9 m / s respectively; Figure 12 Optical photos of the corn samples colliding with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively; Figure 13 Velocity trace diagrams of the collision-diffused dust when the corn samples collide with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively; Figure 14 Optical photos of the wheat samples colliding with the baffle when the installation angles of the baffle are 30°, 45°, 60°, 120°, 135°, and 150° respectively; Figure 15 Velocity trace diagrams of the dust when the wheat samples collide with the baffle when the installation angles of the baffle are 30°, 45°, 60°, 120°, 135°, and 150° respectively; Figure 16 Optical photos of the wheat samples colliding with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s respectively; Figure 17 Velocity trace diagrams of the collision-diffused dust when the wheat samples collide with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s respectively; Figure 18 Optical photos of the wheat samples colliding with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively; Figure 19 Velocity trace diagrams of the collision-diffused dust when the wheat samples collide with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively; Figure 20 Optical photos of the sorghum samples colliding with the baffle when the installation angles of the baffle are 30°, 45°, 60°, 120°, 135°, and 150° respectively; Figure 21 Velocity trace diagrams of the dust when the sorghum samples collide with the baffle when the installation angles of the baffle are 30°, 45°, 60°, 120°, 135°, and 150° respectively; Figure 22 Optical photos of the sorghum samples colliding with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s respectively; Figure 23 Velocity trace diagrams of the collision-diffused dust when the sorghum samples collide with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s respectively; Figure 24Optical photographs of sorghum samples colliding with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively; Figure 25 Velocity trace diagrams of the collision-diffused dust when the sorghum samples collide with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively. Specific implementation manners

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] A dust suppression method for the discharge points of a multi-point discharge closed belt conveyor, which includes the following steps: S1. Build an experimental device for belt conveyor discharge collision dust generation in the laboratory, and conduct an experiment on belt conveyor discharge collision dust generation to determine the conveying speed, collision angle, and grain unloading height of the belt conveyor with the least collision dust generation; S11. Prepare experimental grain samples S111. Prepare a certain amount of grain particles, which are grain particles without shriveled or broken grains; S112. Add a certain amount of tracer particles to the grain particles in step S111 and mix them evenly to obtain experimental grain samples. After the obtained grain samples are equally divided and stored in a constant temperature and humidity box; the tracer particles are micron-sized solid dust, such as glutinous rice flour, etc.; S12. Build an experimental device, as Figure 1 shown S121. Arrange a belt conveyor 1 with adjustable height and speed; The belt conveyor 1 has a length of 2.1 m, a width of 0.4 m, a height adjustment range of 0.1 m to 2.0 m, and a speed adjustment range of 2.1 m / s to 4.1 m / s.

[0029] S122. Set an angle-adjustable baffle 7 corresponding to the discharge end of the belt conveyor 1 in step S121, and adjust the installation angle of the baffle 7; the angle adjustment range of the included angle between the baffle 7 and the horizontal plane is 0 to 180°.

[0030] S123. Arrange a PIV test system; The PIV test system includes a laser illumination device 3, a CCD camera 6, a synchronization controller 4, and a computer 5 equipped with an image analysis system. The lens of the CCD camera 6 faces the baffle 7 directly, the laser illumination device 3 corresponds to the baffle 7, the synchronization controller 4 is communicatively connected to the CCD camera 6 and the laser illumination device 3, and the CCD camera 3 is communicatively connected to the computer 5 equipped with an image analysis system.

[0031] S13. Obtain the installation angle of the baffle 7 with the least collision dust generation S131. Set the height difference between the discharge end of the belt conveyor and the plane of the baffle 7, set the motor frequency corresponding to the conveying speed, set the installation angle of the baffle 7, calibrate the PIV test system, and start the belt conveyor 1; S132. After the belt conveyor 1 runs stably, add a certain amount of the grain sample obtained in step S11 to the belt conveyor 1; S133. When the grain sample is discharged and collides with the baffle 7 at the discharge end of the belt conveyor 1, the PIV test system conducts experimental shooting to obtain multiple corresponding optical photos of the grain sample colliding with the baffle 7; S134. Adjust the installation angle of the baffle 7 multiple times, and calibrate the PIV test system. Repeat steps S132 - S134 to obtain multiple groups of optical photos of the grain sample colliding with the baffle with the same height difference between the discharge end of the belt conveyor and the plane of the baffle, the same conveying speed of the belt conveyor, and different installation angles of the baffle; S135. Use the visualization post - processing software Tecplot to conduct a comparative analysis of the optical photos obtained in step S134 to obtain the velocity trace map of the dust collision and diffusion when the grain sample collides with the baffle; S136. Compare and analyze the optical photos obtained in step S134 and the velocity trace map obtained in step S135 to obtain the installation angle of the baffle with the minimum collision dust emission when the height difference between the discharge end of the belt conveyor and the plane of the baffle is the same and the conveying speed of the belt conveyor is the same.

[0032] S14. Obtain the conveying speed with the minimum collision dust emission S141. Set the height difference between the discharge end of the belt conveyor and the plane of the baffle, set the motor frequency corresponding to the conveying speed, set the installation angle of the baffle, calibrate the PIV test system, and start the belt conveyor; S142. Repeat steps S132 - S133 to obtain multiple optical photos of the grain sample colliding with the baffle with the height difference, conveying speed, and installation angle of the baffle set in step S141; S143. Adjust the motor frequency of the belt conveyor multiple times, and calibrate the PIV test system. Repeat steps S132 - S134 to obtain multiple groups of optical photos of the grain sample colliding with the baffle with the same height difference between the discharge end of the belt conveyor and the plane of the baffle, the same installation angle of the baffle, and different conveying speeds of the belt conveyor; S144. Repeat steps S135 - S136 to obtain the conveying speed of the belt conveyor with the minimum collision dust emission when the height difference between the discharge end of the belt conveyor and the plane of the baffle is the same and the installation angle of the baffle is the same.

[0033] S15. Obtain the height difference between the discharge end of the belt conveyor and the plane of the baffle with the minimum collision dust emission S151. Set the height difference between the discharge end of the belt conveyor and the baffle plane, set the motor frequency corresponding to the conveying speed, set the installation angle of the baffle, calibrate the PIV test system, and start the belt conveyor; S152. Repeat steps S132 - S133 to obtain multiple optical photos of the grain sample colliding with the baffle at the height difference, conveying speed, and baffle installation angle set in step S151; S153. Adjust the height difference between the discharge end of the belt conveyor and the baffle plane multiple times, calibrate the PIV test system, and repeat steps S132 - S134 to obtain multiple optical photos of the grain sample colliding with the baffle when the conveying speed is the same, the baffle installation angle is the same, and the height difference between the discharge end of the belt conveyor and the baffle plane is different; S154. Repeat steps S135 - S136 to obtain the height difference between the discharge end of the belt conveyor and the baffle plane with the smallest collision dust emission when the baffle installation angles are the same.

[0034] S2. Install a discharger in the enclosed belt conveyor according to the conveying speed, grain discharging height, and collision angle of the belt conveyor obtained in step S1.

[0035] As Figures 2 - 7As shown in the figure, a dust suppression unloading device, which includes a housing 8, a high-position roller 9, a low-position roller 10, a high-position conveyor belt 11, a low-position conveyor belt 12 and a discharger 13. A high-position roller 9 and a low-position roller 10 are arranged in the housing 8. The high-position roller 9 is located at the upper part of the housing 8, and the low-position roller 10 is located at the lower part of the housing 8. A height difference is formed between the high-position roller 9 and the low-position roller 10. The high-position roller 9 is located at the discharging end of the high-position conveyor belt 11, and the low-position roller 10 is located at the starting end of the low-position conveyor belt 12. An inclined discharger 13 is arranged between the high-temperature roller and the low-position roller 10. The discharger 13 has a discharge housing 131, a feed inlet 132 at the upper end of the discharge housing 131, a discharge outlet 133 at the lower end of the discharge housing 131 and discharge openings 134 on both sides of the discharge housing 131. The discharge outlet 133 of the discharger 13 corresponds to the low-position conveyor belt 12, and the discharge openings 134 of the discharger 13 are communicated with the discharge bins 14 on both sides of the housing 8. The feed inlet 132 and the discharge outlet 133 are communicated to form a discharge channel, and the feed inlet 132 and the discharge openings 134 are communicated to form a discharging channel. A discharge hopper 15 capable of flipping relative to the discharge housing 131 and a driving device 17 for driving the discharge hopper 15 to flip are arranged in the discharge housing 131. The flipping of the discharge hopper 15 realizes the switching between the discharge channel and the discharging channel. A receiving hopper 16 arranged obliquely is arranged in the feed inlet 132 of the discharger 13. The included angle between the receiving plate 161 of the receiving hopper 16 and the horizontal line is a, and the included angle a is 45° to 60°, preferably 60°. The height difference between the lower edge of the receiving plate 161 and the upper end of the high-position roller 9 is h, and the height h is 200 mm to 300 mm, preferably 200 mm. The included angle a and the height h are both determined by the above experimental method.

[0036] The lower end of the housing 8 is provided with a material collecting port 81 opening downward. Below the material collecting port 81, a material cleaning housing 21 is arranged. On the top plate of the material cleaning housing 21, there is a material cleaning feed port 25 communicating with the material collecting port 81. Inside the material cleaning housing 21, a material collecting plate 82 is arranged. The two sides of the material collecting plate 82 are connected to the side plates of the material cleaning housing 21. At the lower end of one side of the material cleaning housing 21, there is a material cleaning discharge port 18. Inside the material cleaning housing 21, a material cleaning conveying device is arranged. The material cleaning conveying device is used to convey the materials received by the material collecting plate 82 to the material cleaning discharge port 18. The material cleaning discharge port 18 communicates with the material return feed port 19 of the material return housing 20. The material return housing 20 is a square annular hollow housing. The low-position conveyor belt 12 passes through the inner ring square hole of the square annular housing. On one side of the material return housing 20 above the low-position conveyor belt 12, there is a material return discharge port 26 opening upward. The material return discharge port 26 corresponds to the upper conveyor belt of the low-position conveyor belt 12. Inside the material return housing 20, a material return conveying device is arranged. The material return conveying device conveys the materials conveyed by the material cleaning conveying device to the upper conveyor belt of the low-position conveyor belt 12. The material cleaning conveying device is a material cleaning scraper 22 and a material cleaning chain mechanism 23 arranged inside the material cleaning housing 21. The two ends of the material cleaning scraper 22 are respectively connected to the chains of the two material cleaning chain mechanisms 23. The lower end of the material cleaning scraper 22 contacts the top surface of the material collecting plate 82. The two material cleaning chain mechanisms 23 drive the material cleaning scraper 22 to move, and the material cleaning scraper 22 pushes the materials on the material collecting plate 82.

[0037] The material return conveying device is a scraper conveying mechanism, including a material return drive shaft, a material return driving sprocket 26, a material return tensioning shaft, a material return tensioning sprocket 27, a material return redirecting shaft, a material return redirecting sprocket 28 and a material return power device 24. The material return drive shaft is arranged inside the material return housing 20, at a corner of the square material return housing 20. Inside the square material return housing 20, a material return driven shaft, a material return tensioning shaft and a material return redirecting shaft are respectively arranged at the other three corners. Outside the material return housing 20, there is a material return power device 24. The material return power device 24 is connected to the material return drive shaft to drive the material return drive shaft to rotate relative to the material return housing 20. The material return drive shaft is provided with a material return driving sprocket 26. The material return driven shaft is provided with a material return driven sprocket 33. The material return redirecting shaft is provided with a material return redirecting sprocket 28. The material return tensioning shaft is provided with a material return tensioning sprocket 27. The material return driving sprocket 26, the material return driven sprocket 32, the material return redirecting sprocket 28 and the material return tensioning sprocket 27 are connected by a material return chain 29. A plurality of material return scrapers 30 are tightly connected to the material return chain 29. Under the action of the material return power device 24, the material return chain 29 drives the material return scrapers 30 to move inside the square annular material return housing 20. The materials flowing out from the material cleaning discharge port 18 of the material cleaning housing 21 enter the material return housing 20, and then are conveyed to the material return discharge port 31 under the action of the material return scraper 20 and fall onto the upper conveyor belt of the low-position conveyor belt 12 from the material return discharge port 31.

[0038] The discharge hopper 15 includes a bottom plate 151 and arc-shaped baffles 152 fixed on both sides of the bottom plate 151. A rotating shaft is provided on the outer side of the arc-shaped baffle 152, and the rotating shafts on the two arc-shaped baffles 152 are coaxially arranged. The rotating shaft passes through the discharge housing 131 and is connected to the driving device 17, and the driving device 17 drives the rotating shaft to drive the arc-shaped baffle 152 and the bottom plate 151 to flip. Two receiving hoppers 16 are arranged in parallel in the feed inlet 132 of the discharge housing 131. The receiving hopper 16 is a funnel-shaped structure surrounded by a receiving plate 161, an inner wall plate 162, an outer wall plate 163 and a baffle plate 164. The receiving plate 161 and the baffle plate 164 are oppositely arranged, and the inner wall plate 162 and the outer wall plate 163 are oppositely arranged. The inner cavity of the receiving hopper 16 forms a feed channel. Both sides of the discharge port 133 of the discharge housing 131 are provided with discharge plates 135 which are inclined downward from outside to inside, and the two discharge plates 135 respectively correspond to the outer wall plates 163 of the two receiving hoppers 16. The discharge port 134 of the discharge housing 131 is provided with a discharge plate 136 which is inclined downward from inside to outside, and the discharge plates 136 of the two discharge ports 134 respectively correspond to the inner wall plates 162 of the two receiving hoppers 16. When the discharger 13 discharges, the bottom plate 151 of the discharge hopper 15 fits with the inner wall plate 162 and the discharge plate 136 to form a discharge channel, and the feed inlet 132 of the discharge housing 131 is communicated with the discharge port 134. When the discharger 13 discharges materials, the bottom plate 151 of the discharge hopper 15 fits with the outer wall plate 163 and the discharge plate 135 to form a discharge channel, and the feed inlet 132 of the discharge housing 131 is communicated with the discharge port 133. Example 1

[0039] In this example, the transportation of corn by a belt conveyor is taken as an example. By setting the conveying speed, collision angle and grain discharging height of the belt conveyor, the collision dust generation at the discharging points of the multi-point discharging enclosed belt conveyor is reduced.

[0040] A method for suppressing dust at the discharging points of a multi-point discharging enclosed belt conveyor, which includes the following steps: S1. Build an experimental device for dust generation during the discharging and collision of a belt conveyor in a laboratory, and conduct an experiment on dust generation during the discharging and collision of the belt conveyor to determine the conveying speed, collision angle and grain discharging height of the belt conveyor with the least dust generation during the collision.

[0041] S11. Prepare experimental grain samples S111. Prepare a certain amount of corn grains with plump grains, no shriveled grains and broken grains; S112. Add tracer particles to the grain particles in step S111 and mix them evenly to obtain the experimental corn samples. After the obtained corn samples are equally divided and stored in a constant temperature and humidity box; the tracer particles are micron-sized solid dusts, such as glutinous rice flour, etc., and the doping rate of the tracer particles in the mixed corn samples is 15%.

[0042] S12. Set up the experimental device as Figure 1 shown S121. Arrange a belt conveyor with adjustable height and speed; The height adjustment range of the belt conveyor is 1.0 m to 2.0 m, and the speed adjustment range is 2.1 m / s to 4.1 m / s.

[0043] S122. Set up a baffle with adjustable angle corresponding to the discharge end of the belt conveyor in step S121; and adjust the installation angle of the baffle; The angle adjustment range of the included angle between the baffle and the horizontal plane is 0 to 180°.

[0044] S123. Arrange a PIV test system; The PIV test system includes a laser illumination device 3, a CCD camera 6, a synchronization controller 4, and a computer 5 equipped with an image analysis system. The lens of the CCD camera 6 faces the baffle 7 directly. The laser illumination device 3 corresponds to the baffle 7. The synchronization controller 4 is communicatively connected to the CCD camera 6 and the laser illumination device 3. The CCD camera 3 is communicatively connected to the computer 5 equipped with an image analysis system.

[0045] S13. Obtain the installation angle of the baffle with the least collision dust S131. Set the height difference between the discharge end of the belt conveyor and the baffle plane to 200 mm, set the motor frequency corresponding to the conveying speed of 2.1 m / s, set the installation angle of the baffle to 30°, calibrate the PIV test system, and start the belt conveyor.

[0046] S132. After the belt conveyor runs stably, add a certain amount of the grain sample obtained in step S1 to the belt conveyor.

[0047] S133. When the grain sample is discharged and collides with the baffle from the discharge end of the belt conveyor, the PIV test system conducts experimental shooting to obtain multiple corresponding optical photos of the grain sample colliding with the baffle.

[0048] S134. Adjust the installation angles of the baffle to 45°, 60°, 120°, 135°, and 150° respectively, calibrate the PIV test system, and repeat steps S132 to S134 to obtain multiple groups of optical photos of the grain sample colliding with the baffle with the same height difference between the discharge end of the belt conveyor and the baffle plane, the same conveying speed of the belt conveyor, and different installation angles of the baffle; as Figure 8 shown are the optical photos of the corn sample colliding with the baffle when the installation angles of the baffle are 30°, 45°, 60°, 120°, 135°, and 150° respectively.

[0049] S135. Use the visualization post-processing software Tecplot to conduct a comparative analysis of the optical photos obtained in step S134 to obtain the velocity trace map of dust collision and diffusion when the grain sample collides with the baffle; as Figure 9 shown are the velocity trace maps of dust when the corn sample collides with the baffle at baffle installation angles of 30°, 45°, 60°, 120°, 135°, and 150°.

[0050] S136. Compare and analyze the optical photos obtained in step S134 and the velocity trace maps obtained in step S135 to obtain the baffle installation angle with the least collision dust when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the conveying speed of the belt conveyor is the same. As Figure 8 and Figure 9 shown, when the baffle installation angle is adjusted from 30° to 150°, the proportion of collision dust shows a trend of first decreasing and then increasing. When the baffle installation angle is 60°, the generation of collision dust is the least. This indicates that at 60°, more kinetic energy of the grain particles is converted into sliding along the baffle direction rather than generating collision dust. At other angles, the kinetic energy conversion efficiency is low. Especially when the inclination angle is greater than 60°, the rebound kinetic energy increases, resulting in an enlarged dust diffusion range. When the baffle angle changes from 120° to 150°, the dust diffusion range and the amount of dust diffusion gradually increase. The horizontal kinetic energy is gradually converted into vertical kinetic energy, resulting in a significant increase in both dust and collision dust, and the dust diffusion trajectory is complex and the diffusion range is wide. Therefore, when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the conveying speed of the belt conveyor is the same, the baffle installation angle with the least collision dust is 60°.

[0051] S14. Obtain the conveying speed with the least collision dust S141. Set the height difference between the discharge end of the belt conveyor and the baffle plane to 200 mm, set the motor frequency corresponding to the conveying speed of 2.1 m / s, set the installation angle of the baffle to 30°, calibrate the PIV test system, and start the belt conveyor.

[0052] S142. Repeat steps S132 - S133 to obtain multiple optical photos of the grain sample colliding with the baffle when the height difference between the discharge end of the belt conveyor and the baffle plane is 200 mm, the conveying speed is 2.1 m / s, and the installation angle of the baffle is 30°.

[0053] S143. Adjust the conveying speed of the belt conveyor to the motor frequencies corresponding to 3.1 m / s, 4.1 m / s, and 4.9 m / s respectively, calibrate the PIV test system, and repeat steps S132 - S134 to obtain multiple groups of optical photos of the grain sample colliding with the baffle when the height difference between the discharge end of the belt conveyor and the baffle plane is the same, the baffle installation angle is the same, and the conveying speed of the belt conveyor is different. As Figure 10Shown are the optical photos of the corn samples colliding with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, 4.1 m / s, and 4.9 m / s respectively. As Figure 11 Shown is the velocity trace diagram of the collision-diffused dust when the corn samples collide with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, 4.1 m / s, and 4.9 m / s respectively.

[0054] S144. Repeat steps S135 - S136 to obtain the conveying speed of the belt conveyor with the least collision dust emission when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the baffle installation angle is the same.

[0055] When the conveying speed of the belt conveyor is 2.1 m / s, the dust diffusion speed generated by the grain samples hitting the baffle is mostly controlled below 0.3 m / s; when the conveying speed is 3.1 m / s, the generated dust diffusion speed is mostly below 0.6 m / s; when the conveying speed is 4.1 m / s, the generated dust diffusion speed is about 1.1 m / s; when the conveying speed is 4.9 m / s, the generated dust diffusion speed is about 1.3 m / s. From Figure 10 and Figure 11 it can be seen that when the conveying speed is low, the proportion of dust emission is larger than that of collision dust, and the dust diffusion trajectory mainly moves along the direction of contacting the baffle, showing a strong tendency to diffuse along the plate. When the conveyor belt speed is high, the proportion of collision dust is larger than that of dust emission, the collision dust diffusion effect is obvious, the dust diffusion moves perpendicular to the baffle direction, and the eddy current distribution is significant. Thus, it can be known that as the conveying speed of the belt conveyor increases, the grain dust diffusion speed is greater, and the eddy current distribution is more obvious. Its dust diffusion range also increases with the increase of speed. Therefore, when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the baffle installation angle is the same, the conveying speed of the belt conveyor with the least collision dust emission is 2.1 m / s.

[0056] S15. Obtain the height difference between the discharge end of the belt conveyor with the least collision dust emission and the baffle plane S151. Set the height difference between the discharge end of the belt conveyor and the baffle plane to 200 mm, set the motor frequency corresponding to the conveying speed of 2.1 m / s, set the installation angle of the baffle to 30°, calibrate the PIV test system, and start the belt conveyor.

[0057] S152. Repeat steps S132 - S133 to obtain multiple optical photos of the grain samples colliding with the baffle when the height difference between the discharge end of the belt conveyor and the baffle plane is 200 mm, the conveying speed is 2.1 m / s, and the installation angle of the baffle is 30°.

[0058] S153. Adjust the height differences between the discharge end of the belt conveyor and the baffle plane to 350 mm and 500 mm respectively, calibrate the PIV test system, and repeat steps S132 - S134 to obtain optical photos of multiple groups of grain samples colliding with the baffle when the conveying speed is the same, the baffle installation angle is the same, and the height differences between the discharge end of the belt conveyor and the baffle plane are different. As Figure 12 shown are the optical photos of corn samples colliding with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively. As Figure 13 shown is the velocity trace diagram of the collision - diffused dust when corn samples collide with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively.

[0059] S154. Repeat steps S135 - S136 to obtain the height difference between the discharge end of the belt conveyor and the baffle plane with the smallest collision dust emission when the baffle installation angles are the same.

[0060] The height difference between the discharge end of the belt conveyor and the baffle plane is the falling height of the grain. As shown by Figure 12 and Figure 13 , different grain falling heights have a significant impact on dust diffusion. At a lower falling height, the kinetic energy of the grain particles is lower, the collision dust generated when hitting the baffle is less, and the amount of dust emission is also less. The dust diffusion range is smaller. As the falling height increases, the kinetic energy of the grain particles increases, and a large amount of collision dust and dust emission are generated. The dust diffusion range is the largest, and the diffusion trajectory is complex, mainly diffusing along the baffle direction and the vertical direction, and generating an eddy - current effect. In addition, as the grain falling height increases, the dust diffusion concentration continuously increases. This phenomenon is because as the falling height increases, the kinetic energy of the grain increases, and the intensity of the induced air flow also increases. After the collision, the speed of the grain changes rapidly, resulting in a larger collision intensity, and the larger induced air flow also increases the probability of dust diffusion on the grain surface, promoting the secondary dust - emission phenomenon, thus leading to more obvious dust diffusion as the height increases. As can be seen from Figure 13 the velocity trace diagram, as the grain falling height increases, the vertical - direction component velocity of the dust increases, the dust diffusion speed increases significantly, the dust diffusion range and concentration increase, and the diffusion trajectory becomes more complex, and it is easy to generate dust eddies. Therefore, when the baffle installation angles are the same, the height difference between the discharge end of the belt conveyor and the baffle plane with the smallest collision dust emission is 200 mm.

[0061] S2. Install a discharger in the closed - type belt conveyor according to the conveying speed, grain - discharging height, and collision angle of the belt conveyor obtained in step S1. Example Two

[0062] Repeat Example 1. In this example, a belt conveyor is used to transport wheat as an example. By setting the conveying speed, collision angle, and unloading height of the belt conveyor, the collision dust generation at the unloading points of the multi-point unloading enclosed belt conveyor is reduced.

[0063] Figure 14 The following are the optical photos of the wheat sample colliding with the baffle when the baffle installation angles are 30°, 45°, 60°, 120°, 135°, and 150° respectively.

[0064] Figure 15 The following are the velocity trace diagrams of the dust generated by the collision of the wheat sample with the baffle when the baffle installation angles are 30°, 45°, 60°, 120°, 135°, and 150° respectively.

[0065] Figure 16 The following are the optical photos of the wheat sample colliding with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s respectively.

[0066] Figure 17 The following are the velocity trace diagrams of the diffused dust generated by the collision of the wheat sample with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s respectively.

[0067] Figure 18 The following are the optical photos of the wheat sample colliding with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively.

[0068] Figure 19 The following are the velocity trace diagrams of the diffused dust generated by the collision of the wheat sample with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm respectively.

[0069] From Figure 14 and Figure 15 it can be seen that when the baffle installation angle is between 45° and 60°, the throwing trajectory of the wheat sample tends to be consistent with the baffle plane, the amount of collision dust generated is the least, and the dust is mainly the dust rising along the baffle direction. This indicates that a medium inclination angle helps to reduce the secondary diffusion of dust, making the dust concentrate on the baffle surface and flow, reducing the diffusion range of dust. When the baffle installation angle is 60°, the dust in the wheat sample is more inclined to slide along the baffle, and the collision dust is the least; when the baffle installation angle increases from 120° to 150°, the vertical kinetic energy of the dust increases, resulting in a wider diffusion and a more complex trajectory. Therefore, the baffle installation angle with the least collision dust generation is 60°.

[0070] From Figure 16 and Figure 17It can be seen that the dust diffusion behavior of wheat samples is significantly different at different conveying speeds. With the increase of the conveying speed, the dust diffusion speed generated when the wheat samples impact the baffle plate increases significantly, and the dust diffusion range also expands accordingly. This characteristic is consistent with the experimental results of corn samples, but the dust generation and diffusion characteristics of wheat samples are more obvious. However, due to the smaller particle size of wheat than that of corn, its movement activity during the collision process is higher, resulting in a higher dust generation rate. When the conveying speed is 2.1 m / s, the dust diffusion speed in wheat samples is about 1.3 times that of corn, and the diffusion range expands by about 25%. This phenomenon is because wheat particles are more likely to break and generate fine dust when colliding with each other, while corn generates less dust under similar conditions due to its larger particle size and stronger structural stability. In addition, the diffusion of wheat dust particles can more effectively enhance the intensity of the induced air flow. When the conveyor belt speed increases to 4.1 m / s, the diffusion trajectory of wheat dust becomes more complex, the diffusion range expands by nearly 50%, and it is easier to form a vortex phenomenon. In contrast, due to the larger particle size of corn dust, the diffusion trajectory is relatively simple and the vortex phenomenon is not obvious. Therefore, the conveying speed with the least collision dust is 2.1 m / s.

[0071] In summary, at high conveyor speeds, due to its smaller particle size and higher movement activity, wheat results in greater dust generation and diffusion intensity, which has a more significant impact on the environment and production process. This indicates that more attention needs to be paid to the control of conveyor speed in actual operation to reduce the impact of dust on the environment.

[0072] It can be seen from Figure 18 and Figure 19 that different falling heights of wheat have a significant impact on dust diffusion. At a relatively low falling height of 200 mm, the kinetic energy of wheat particles is low, less collision dust is generated when impacting the baffle plate, and the amount of dust raised is also small. The dust diffusion range is small. As the falling height increases, the kinetic energy of the grain particles increases, and a large amount of collision dust and dust raised are generated. The dust diffusion range is the largest, the diffusion trajectory is complex, mainly diffusing along the baffle direction and the vertical direction, and a significant vortex effect is generated. As the falling height increases, the vertical component velocity of wheat dust increases, the dust diffusion speed increases significantly with the increase of height, the dust diffusion range and concentration increase, the diffusion trajectory becomes more complex, and it is easy to generate dust vortices. The particle size of grain dust particles will affect their movement and settlement speed in the air flow. The particle size of wheat is smaller than that of corn, and it is more likely to collide and break away to generate collision dust. The effect of generating collision dust is better than that of corn particles. The diffusion range of the dust generated by the collision is large, the intensity of the induced air flow is enhanced, and it is easier to generate vortex phenomena. Therefore, the falling height with the least collision dust is 200 mm. Example 3

[0073] Repeat Example 1. In this example, a belt conveyor is used to transport sorghum as an example. By setting the conveying speed, collision angle, and unloading height of the belt conveyor, the collision dust generation at the unloading point of the multi-point unloading enclosed belt conveyor is reduced.

[0074] Figure 20 The optical photos of the sorghum sample colliding with the baffle when the baffle installation angles are 30°, 45°, 60°, 120°, 135°, and 150° are shown.

[0075] Figure 21 The velocity trace diagrams of the dust generated by the collision of the sorghum sample with the baffle when the baffle installation angles are 30°, 45°, 60°, 120°, 135°, and 150° are shown.

[0076] Figure 22 The optical photos of the sorghum sample colliding with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s are shown.

[0077] Figure 23 The velocity trace diagrams of the diffused dust generated by the collision of the sorghum sample with the baffle when the conveying speeds of the belt conveyor are 2.1 m / s, 3.1 m / s, and 4.1 m / s are shown.

[0078] Figure 24 The optical photos of the sorghum sample colliding with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm are shown.

[0079] Figure 25 The velocity trace diagrams of the diffused dust generated by the collision of the sorghum sample with the baffle when the conveying speeds of the belt conveyor are 200 mm, 350 mm, and 500 mm are shown.

[0080] From Figure 20 and Figure 21It can be seen that with the change of the baffle installation angle, the dust diffusion behavior of sorghum samples during collision shows obvious regularity. When the baffle installation angle increases from 120° to 150°, the diversity of the rebound direction of the collision dust is significantly enhanced, resulting in a more complex flow pattern and an obvious eddy current effect. The dust particles are easily suspended and spread to a wider area, and both the dust raised by the wind and the collision dust increase significantly, with the widest diffusion range. When the baffle installation angles are 45° and 60°, the sorghum throwing trajectory is similar to the baffle plane, and the generated dust is mainly the dust raised by the wind. The movement trend of the dust is downward along the baffle direction. The sorghum grains mainly slide downward along the baffle, generating less collision dust. The dust diffusion is relatively concentrated and the range is small. When the baffle installation angle changes from 120° to 150°, the sorghum dust diffusion range and the amount of dust raised by the wind gradually increase. The horizontal kinetic energy is gradually converted into vertical kinetic energy, resulting in a significant increase in both the dust raised by the wind and the collision dust. The dust diffusion trajectory is complex and the diffusion range becomes wider. The dust diffusion moves perpendicular to the baffle direction, and the eddy current distribution is significant. Therefore, the baffle installation angle with the least collision dust is 60°.

[0081] It can be seen from Figure 22 and Figure 23 that different conveying speeds have a significant impact on dust diffusion. It can be seen from the velocity trace diagram that the diffusion speed of sorghum dust generated by hitting the baffle increases with the increase of the conveyor belt speed, and the corresponding dust diffusion range also increases. This characteristic is the same as the relevant experimental conclusions of corn, wheat, etc.

[0082] Sorghum grains are small, and dust is relatively easy to adhere to their surfaces. There are more impurities such as dust adsorbed on their surfaces. A higher conveying speed will intensify the impact force between the grains and the baffle, resulting in more dust detaching from the grain surfaces and spreading. The range of collision dust generated after collision is larger than that in the corn collision experiment. The diffusion of sorghum dust particles can more effectively disturb and enhance the intensity of the induced air flow. With the increase of the sorghum grain conveying speed, when the grain conveying speed of the conveyor belt is 4.1 m / s, the eddy current phenomenon is the most obvious, and the eddy current disturbance also causes the dust diffusion range after collision to further increase. Therefore, the conveying speed with the least collision dust is 2.1 m / s.

[0083] It can be seen from Figure 24 and Figure 25 that similar to corn and wheat, the dust diffusion of sorghum is significantly affected by the falling height. During the sorghum grain transportation process, different falling heights have a significant impact on dust diffusion. The increase in the falling height will lead to an increase in the amount of dust generated. With the increase of the falling height, the kinetic energy of the grain increases, and the amounts of collision dust and dust raised by the wind generated increase significantly. During the experiment, when the falling height is 500 mm, the dust diffusion range is the largest, the diffusion trajectory is complex, and the dust diffusion mainly spreads along the baffle direction. Therefore, the falling height with the least collision dust is 200 mm.

[0084] As the falling height continuously increases, the vertical component velocity of sorghum grains increases, and the initial velocity of dust diffusion increases significantly with the height. The dust diffusion trajectory becomes more complex, prone to forming an eddy current effect, exacerbating the diffusion of dust in the air and increasing environmental pollution.

[0085] Compared with corn and wheat, sorghum grains are lighter in mass and smaller in particle size. This makes the dust particles generated during the collision of sorghum smaller and more easily carried by the airflow, forming a more complex diffusion trajectory. In contrast, due to its larger particle size and mass, the dust particles of corn are larger, the sedimentation velocity is faster, and the suspension time is shorter. Wheat is between the two, and its dust generation and diffusion characteristics are between sorghum and corn.

[0086] It should be noted that the above-described embodiments are illustrative rather than restrictive of the technical solutions of the present invention. Equivalent substitutions by those of ordinary skill in the art or other modifications made according to the prior art, as long as they do not exceed the scope and spirit of the technical solutions of the present invention, should be included within the scope of the claims required by the present invention.

Claims

1. A method for suppressing dust at the unloading point of a multi-point unloading closed belt conveyor, characterized in that: The following steps are involved: S1. Build a belt conveyor unloading collision dust test device in the laboratory, and conduct a belt conveyor unloading collision dust test to determine the conveying speed, collision angle and unloading height of the belt conveyor with the smallest collision dust; S2. Install a discharger in the closed belt conveyor according to the conveying speed, grain unloading height and collision angle of the belt conveyor obtained in step S1.

2. The method for suppressing dust at the unloading point of a multi-point unloading closed belt conveyor according to claim 1, characterized in that: The belt conveyor unloading collision dust experiment in step S1 includes the following steps: S11. Prepare experimental grain samples S111, preparing a certain amount of grains with full grains and no shriveled grains or broken grains; S112, adding a certain amount of tracer particles to the grain particles in step S111 and mixing them evenly to obtain grain samples for experiments, and packaging the obtained grain samples in equal amounts and storing them in a constant temperature and humidity chamber; S12. Build the experimental device S121, arrange a belt conveyor with adjustable height and speed; S122, setting an angle-adjustable baffle corresponding to the discharge end of the belt conveyor in step S121; S123, arrange the PIV test system; S13. Obtain the baffle installation angle with the minimum collision dust S131, setting the height difference between the belt conveyor discharge end and the baffle plane, setting the motor frequency corresponding to the conveying speed, setting the installation angle of the baffle, calibrating the PIV test system, and starting the belt conveyor; S132, after the belt conveyor runs stably, add a portion of the grain sample obtained in step S11 to the belt conveyor; S133, when the grain sample is thrown from the discharge end of the belt conveyor and collides with the baffle, the PIV test system performs experimental shooting to obtain a plurality of corresponding optical photos of the grain sample colliding with the baffle; S134, adjusting the baffle installation angle multiple times, calibrating the PIV test system, repeating steps S132 to S134, and obtaining optical photographs of multiple groups of grain samples colliding with the baffle with the same height difference between the belt conveyor discharge end and the baffle plane, the same belt conveyor conveying speed, and different baffle installation angles; S135, using the visualization post-processing software Tecplot to compare and analyze the optical photos obtained in step S134, and obtain a velocity trace diagram of dust collision diffusion when the grain sample collides with the baffle; S136, comparing and analyzing the optical photograph obtained in step S134 and the velocity trace diagram obtained in step S135, obtaining the baffle installation angle with the smallest collision dust when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the conveying speed of the belt conveyor is the same; S14. Obtain the minimum conveying speed of collision dust S141, setting the height difference between the belt conveyor discharge end and the baffle plane, setting the motor frequency corresponding to the conveying speed, setting the installation angle of the baffle, calibrating the PIV test system, and starting the belt conveyor; S142, repeating steps S132 to S133 to obtain a plurality of optical photographs of the grain sample colliding with the baffle; S143, adjusting the motor frequency of the belt conveyor multiple times, calibrating the PIV test system, repeating steps S132 to S134, obtaining optical photographs of multiple groups of grain samples colliding with the baffle plate with the same height difference between the belt conveyor discharge end and the baffle plate plane, the same baffle plate installation angle, and different belt conveyor conveying speeds; S144, repeating steps S135-S136 to obtain the conveying speed of the belt conveyor with the smallest collision dust when the height difference between the discharge end of the belt conveyor and the baffle plane is the same and the baffle installation angle is the same; S15. Obtain the height difference between the belt conveyor discharge end and the baffle plane with the smallest collision dust S151, setting the height difference between the belt conveyor discharge end and the baffle plane, setting the motor frequency corresponding to the conveying speed, setting the installation angle of the baffle, calibrating the PIV test system, and starting the belt conveyor; S152, repeating steps S132 to S133 to obtain a plurality of optical photographs of the grain sample colliding with the baffle; S153, adjusting the height difference between the belt conveyor discharge end and the baffle plane for multiple times, and calibrating the PIV test system, repeating steps S132 to S134, and obtaining optical photographs of multiple groups of grain samples colliding with the baffle with the same conveying speed, the same baffle installation angle, and different height differences between the belt conveyor discharge end and the baffle plane; S154, repeating steps S135-S136 to obtain a height difference between the belt conveyor discharge end and the baffle plane with the minimum collision dust when the baffle installation angle is the same.

3. The dust suppression method at the unloading point of a multi-point unloading closed belt conveyor according to claim 2 is characterized in that: Preferably, in step S112, the tracer particles are micron-sized solid dust.

4. The dust suppression method at the unloading point of a multi-point unloading closed belt conveyor according to claim 2 is characterized in that: In step S121, the height adjustment range of the belt conveyor is 0.1m~2.0m, and the speed adjustment range is 2.1m / s~4.1m / s.

5. The dust suppression method at the unloading point of a multi-point unloading closed belt conveyor according to claim 2 is characterized in that: In step S122, the angle between the baffle and the horizontal plane is adjusted in the range of 0 to 180 degrees.

6. The method for suppressing dust at unloading points of a multi-point unloading enclosed belt conveyor according to any one of claims 2 to 5, characterized in that: The PIV testing system includes a laser lighting device, a CCD camera, a synchronous controller and a computer equipped with an image analysis system. The lens of the CCD camera faces the baffle, the laser lighting device faces the baffle, the synchronous controller is communicatively connected with the CCD camera and the laser lighting device, and the CCD camera is communicatively connected with the computer equipped with the image analysis system.

7. A dust suppression and unloading device, characterized in that: it includes a shell, a high roller, a low roller, a high conveyor belt, a low conveyor belt and a discharger, the shell is provided with a high roller and a low roller, the high roller is located at the upper part of the shell, the low roller is located at the lower part of the shell, a drop is formed between the high roller and the low roller, the high roller is located at the discharge end of the high conveyor belt, the low roller is located at the starting end of the low conveyor belt, an inclined discharger is arranged between the high-temperature roller and the low roller, the discharger has a discharge shell, a feed port at the upper end of the discharge shell, a discharge port at the lower end of the discharge shell and discharge ports on both sides of the discharge shell, the discharge port of the discharger Corresponding to the low-level conveyor belt, the discharge port of the discharger is connected with the discharge boxes on both sides of the shell, the feed port and the discharge port are connected to form a discharge channel, and the feed port and the discharge port are connected to form a discharge channel. A discharge hopper capable of flipping relative to the discharge shell and a driving device for driving the discharge hopper to flip are provided in the discharge shell, and the flipping of the discharge hopper realizes the switching of the discharge channel and the discharge channel. A receiving hopper arranged obliquely is provided in the feed port of the discharger, and the angle between the receiving plate of the receiving hopper and the horizontal line is a, and the height difference between the receiving plate and the upper end of the high-level roller is h, and the angle a and height h are both determined by the dust suppression method described in any one of claims 1 to 6.

8. The dust suppression and discharge device according to claim 7, characterized in that: The angle a is 45-60°, and the height h is 200-300 mm.

9. The dust suppression and discharge device according to claim 7, characterized in that: The lower end of the shell is provided with a collection port opening downward, and a cleaning shell is provided below the collection port, and a cleaning feed port connected to the collection port is provided on the top plate of the cleaning shell, and a collection plate is provided in the cleaning shell, and both sides of the collection plate are connected to the side plates of the cleaning shell, and a cleaning discharge port is provided at the lower end of one side of the cleaning shell, and a cleaning conveying device is provided in the cleaning shell, and the cleaning conveying device is used to convey the material received by the collection plate to the cleaning discharge port, and the cleaning discharge port is connected to the return material feed port of the return material shell, and the return material shell is a square annular hollow shell, and the low-level conveyor belt passes through the inner ring square hole of the square annular shell, and a return material discharge port opening upward is provided on one side of the return material shell located above the low-level conveyor belt, and the return material discharge port corresponds to the upper conveyor belt of the low-level conveyor belt, and a return material conveying device is provided in the return material shell, and the return material conveying device conveys the material conveyed by the cleaning conveying device to the upper conveyor belt of the low-level conveyor belt.

10. The dust suppression and discharge device according to claim 7, characterized in that: Two material receiving hoppers are arranged in parallel in the feed port of the discharge shell, and the material receiving hopper is a funnel-shaped structure surrounded by a material receiving plate, an inner wall plate, an outer wall plate and a material baffle plate. The material receiving plate and the material baffle plate are arranged opposite to each other, and the inner wall plate and the outer wall plate are arranged opposite to each other, and the inner cavity of the material receiving hopper forms a feeding channel, and both sides of the discharge port of the discharge shell have discharge plates arranged obliquely downward from the outside to the inside, and the two discharge plates respectively correspond to the outer wall plates of the two receiving hoppers, and the discharge port of the discharge shell is provided with a discharge plate arranged obliquely downward from the inside to the outside, and the discharge plates of the two discharge ports respectively correspond to the inner wall plates of the two receiving hoppers, when the discharger unloads, the bottom plate of the discharge hopper fits with the inner wall plate and the discharge plate to form a discharge channel, and the feed port of the discharge shell is connected with the discharge port, and when the discharger discharges, the bottom plate of the discharge hopper fits with the outer wall plate and the discharge plate to form a discharge channel, and the feed port of the discharge shell is connected with the discharge port.

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